/* Copyright (c) 1997-2019
   Ewgenij Gawrilow, Michael Joswig, and the polymake team
   Technische Universität Berlin, Germany
   https://polymake.org

   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the
   Free Software Foundation; either version 2, or (at your option) any
   later version: http://www.gnu.org/licenses/gpl.txt.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
--------------------------------------------------------------------------------
*/

#include "polymake/client.h"
#include "polymake/graph/lattice_builder.h"
#include "polymake/topaz/hasse_diagram.h"

namespace polymake { namespace topaz {

using namespace graph;
using namespace graph::lattice;

Lattice<BasicDecoration> hasse_diagram_from_facets( const Array<Set<int>>&facets, const RankRestriction& rr)
{
   const Set<int> all_vertices = accumulate(facets, operations::add());
   const int n_vertices = accumulate(all_vertices, operations::max())+1;
   const IncidenceMatrix<> maximal_cells(facets.size(), n_vertices, entire(facets));
      
   if (rr.rank_restricted && rr.rank_restriction_type == RankCutType::LesserEqual)
      throw std::runtime_error("Hasse diagram of SimplicialComplex is always built dually.");
   const Set<int> artificial_set = scalar2set(-1);
   int top_rank = 0;
   if (!facets.empty()) {
      for (auto f : facets) top_rank = std::max(top_rank, f.size());
      ++top_rank;
   }
   SimplicialClosure<BasicDecoration> closure(maximal_cells);
   SimplicialDecorator decorator(top_rank, artificial_set);
   if (!rr.rank_restricted) {
      return lattice_builder::compute_lattice_from_closure<BasicDecoration>(
               closure, TrivialCut<BasicDecoration>(), decorator, false, lattice_builder::Dual());
   } else {
      const auto cut_above = lattice::RankCut<lattice::BasicDecoration, lattice::RankCutType::GreaterEqual>(rr.boundary_rank);
      return lattice_builder::compute_lattice_from_closure<BasicDecoration>(
               closure, cut_above, decorator, rr.boundary_rank > 0, lattice_builder::Dual());
   }
}

perl::Object hasse_diagram_caller(perl::Object complex, const RankRestriction& rr)
{
   const Array<Set<int>>& facets = complex.give("FACETS");
   return static_cast<perl::Object>(hasse_diagram_from_facets(facets, rr));
}

perl::Object hasse_diagram(perl::Object complex)
{
   return hasse_diagram_caller(complex, RankRestriction());
}

perl::Object upper_hasse_diagram(perl::Object complex, int boundary_rank)
{
   return hasse_diagram_caller(complex, RankRestriction(true, RankCutType::GreaterEqual, boundary_rank));
}

Function4perl(&hasse_diagram, "hasse_diagram(SimplicialComplex)");
Function4perl(&upper_hasse_diagram, "upper_hasse_diagram(SimplicialComplex, $)");

} }

// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
